VPLS技术及其应用

以太网技术正以前所未有的速度向前发展，并向城域网迈进。在众多城域以太网技术中，虚拟专用局域网业务（VPLS）作为一种二层虚拟专用网（VPN）技术，由于技术简单可靠、易于实现等优点而广受关注。VPLS有效结合了互联网协议／多协议标签交换（IP／MPLS）、VPN和以太网交换等多种技术的特点，实现厂域范围的多点到多点局域网（LAN）互连，其核心技术包括控制平面的基于标记分发协议（LDP）或边界网关协议（BGP）的伪线建立与维护、数据平面的媒体访问控制（MAC）地址学习、传送平面的伪线封装等。通过分层结构，VPLS可以跨域提供虚拟局域网业务。基于其独特的技术优势，VPLS可以提供大客户二层VPN、城域基础网络建设、个人分布式业务等多个层次的应用。

VPLS Technology and Its Applications

The Ethernet has experienced unprecedented progress of development,and is evolving forward as a metro area carrier grade transport alternative.Among all the metro-Ethernet technologies,Virtual Private LAN Service(VPLS),a layer 2 Virtual Private Network(VPN) technology,is widely used due to its simplicity,reliability,and ease of deployment.With the integration of IP/Multi Protocol Label Switching(MPLS),VPN and Ethernet switching,VPLS is capable of providing multipoint-to-multipoint emulated Local Area Network(LAN) service.The key elements of VPLS include Label Distribution Protocol(LDP)/Border Gateway Protocol(BGP) based on pseudo-wire setup and maintenance in the control plane,Media Access Control(MAC) address learning in the data plane and pseudo-wire encapsulation in the transport plane.Hierarchical architecture can be used to create VPLS service that spans multiple service provider domains.Owing to its unique technical advantages,the applications of VPLS may cover lay 2 VPN for business customers,municipal communication infrastructure and personal distributed services,etc.